ITER Tokamak Fusion Reactor

ITER (International Thermonuclear Experimental Reactor) is being built in Cadarache, France, by a consortium of the EU, US, China, Japan, Russia, South Korea, and India. It is the world's largest tokamak fusion reactor, designed to demonstrate that fusion can produce net energy — generating 500 MW of thermal power from 50 MW of heating input.

The project has experienced significant delays and cost overruns (current estimates exceed €20B), but a 2026 progress report confirmed continued advancement toward first plasma. The ITER Council endorsed the revised timeline, and machine assembly is ongoing. The feasibility of the next step — the DEMO demonstration reactor — depends on ITER's results.

Regardless of timeline criticisms, ITER represents the most advanced fusion engineering project ever attempted. The technologies developed for ITER — superconducting magnets, plasma heating systems, tritium handling, materials science — are being commercialized by private fusion startups worldwide. Europe hosts ITER and maintains the deepest institutional knowledge of tokamak engineering.